The Astrophysical Journal最新文献_第3页

FAST Reveals the Extended H i Halo and Accretion Signatures of NGC 2683 FAST揭示了NGC 2683的扩展H光晕和吸积特征

The Astrophysical Journal Pub Date : 2025-06-04 DOI: 10.3847/1538-4357/add0ba

Qian Jiao, Ming Zhu, Bernd Vollmer, Mei Ai, Haiyang Yu, Qinghua Tan, Cheng Cheng and Yang Gao

{"title":"FAST Reveals the Extended H i Halo and Accretion Signatures of NGC 2683","authors":"Qian Jiao, Ming Zhu, Bernd Vollmer, Mei Ai, Haiyang Yu, Qinghua Tan, Cheng Cheng and Yang Gao","doi":"10.3847/1538-4357/add0ba","DOIUrl":"https://doi.org/10.3847/1538-4357/add0ba","url":null,"abstract":"We present the results of our recent H i observations conducted on the edge-on galaxy NGC 2683 using the Five-hundred-meter Aperture Spherical radio Telescope (FAST). In comparison to previous observations made by the Very Large Array (VLA), FAST has detected a more extensive distribution of H i. Particularly noteworthy is that the detections made by FAST extend approximately 4 times farther than those of the VLA in the vertical direction from the galactic plane. The total H i flux measured for NGC 2683 amounts to FH i = 112.1 Jy km s−1 (equivalent to a total H i mass of MH i = 2.32 × 109M⊙), which is slightly higher than that detected by VLA. FAST has also identified three dwarf galaxies in close proximity to NGC 2683, namely KK 69, NGC 2683dw1, and NGC 2683dw3? (hereafter dw3?). dw3? is situated within the extended H i distribution of NGC 2683 in projection and lies near the tail of KK 69 extending toward NGC 2683. These observations suggest that dw3? is likely a result of the accretion process from NGC 2683 to KK 69. Furthermore, FAST has detected three high-velocity clouds, with complex B potentially undergoing accretion with NGC 2683. Based on the model from B. Vollmer et al. and incorporating the H i halo component, we found that the model with the added H i halo aligns more closely with our FAST observations in NGC 2683. The estimated mass of this H i halo is 3 × 108M⊙, constituting approximately 13% of the total H i mass of the galaxy. We suggest that the origination of this H i halo is more likely attributed to external gas accretion.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"59 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144218825","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Thermally Induced Electromagnetic Fluctuations by Protons and Alpha Particles in the Solar Wind 太阳风中质子和α粒子的热感应电磁波动

The Astrophysical Journal Pub Date : 2025-06-04 DOI: 10.3847/1538-4357/add3fa

Rafael O. Medina, Benjamin Toledo, Roberto E. Navarro and Juan A. Valdivia

{"title":"Thermally Induced Electromagnetic Fluctuations by Protons and Alpha Particles in the Solar Wind","authors":"Rafael O. Medina, Benjamin Toledo, Roberto E. Navarro and Juan A. Valdivia","doi":"10.3847/1538-4357/add3fa","DOIUrl":"https://doi.org/10.3847/1538-4357/add3fa","url":null,"abstract":"We present an initial study on the contribution of alpha particles, alongside electrons and protons, to the generation of thermally induced electromagnetic fluctuations (TIEFs) in space plasmas, such as the solar wind. The inclusion of alpha particles is anticipated to influence the regulation of the quasi-stable region in the beta-anisotropy diagram for both ion species, as well as the amplitude of the fluctuations. For this analysis, we filtered 30 yr of solar wind data at 1 au, focusing on conditions close to isotropy for protons and alpha particles, given that the observational distribution peaks near this state. The filtered data are displayed and organized in the (β∥p, β∥α) plane, where β∥ denotes the ratio of parallel plasma pressure to magnetic pressure for protons (p) and alpha particles (α). In this plane, we analyze the ratio of alpha particle to proton density, nα/np, the squared perpendicular magnetic fluctuations, and compressibility. Furthermore, we compare these magnetic fluctuations with the total fluctuating magnetic energy density derived from a generalized fluctuation–dissipation theorem, highlighting a clear similarity. We also present Fourier spectra for a subset of the data and the corresponding theoretical curve predicted by TIEFs. This study suggests that TIEFs may play a significant role in explaining the unexpected fluctuations observed in space plasmas. Additionally, it provides preliminary evidence that the inclusion of additional ion species could serve as a quantitative test for the theoretical models proposed to describe these fluctuations.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"13 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144218828","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Electrostatic Field Formed by Charge Separation in Antiparallel Magnetic Reconnection 反平行磁重联中电荷分离形成的静电场

The Astrophysical Journal Pub Date : 2025-06-04 DOI: 10.3847/1538-4357/add694

Shihang Hu, Quanming Lu, Yukang Shu, San Lu, Kai Huang and Jia Nan

{"title":"Electrostatic Field Formed by Charge Separation in Antiparallel Magnetic Reconnection","authors":"Shihang Hu, Quanming Lu, Yukang Shu, San Lu, Kai Huang and Jia Nan","doi":"10.3847/1538-4357/add694","DOIUrl":"https://doi.org/10.3847/1538-4357/add694","url":null,"abstract":"The Hall effect resulting from the decoupled motions between ions and electrons is a critical factor in modeling collisionless magnetic reconnection. It leads to the production of charge separation in the reconnection plane, generating the electrostatic field with components perpendicular and parallel to the magnetic field. In this paper, using a 2.5-dimensional particle-in-cell simulation, we investigate the formation of the charge separation in antiparallel magnetic reconnection. The charge separation is formed in three regions: the electron inflow region and the dipolarization front (DF) region both exhibit a positive charge density, while the electron outflow region exhibits a negative charge density. These charge separations generate the Hall electric field perpendicular to the magnetic field and the parallel electrostatic field. We quantitatively analyze the effects of the magnetic flux tube’s geometric dimensions and the parallel electron flux on the formation of charge separation. In the electron inflow region, the parallel electron flux from regions with smaller cross sections to regions with larger cross sections reduces electron density, generating a positive charge density near the separatrix. In contrast, within the outflow region, the parallel electron flux from regions with larger cross sections to regions with smaller cross sections increases electron density, generating a negative charge density near the separatrix. Besides, we attribute the charge separation in the DF region mainly to the acceleration of electrons, which generates a sharply varying parallel electron flux. This drives a net outflow of electrons and establishes an accumulation of positive charge.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144218830","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Unveiling Physical Conditions and Star Formation Processes in the G47 Filamentary Cloud 揭示G47丝状云的物理条件和恒星形成过程

The Astrophysical Journal Pub Date : 2025-06-04 DOI: 10.3847/1538-4357/adcee4

O. R. Jadhav, L. K. Dewangan, A. Haj Ismail, N. K. Bhadari, A. K. Maity, Ram Kesh Yadav, Moustafa Salouci, Patricio Sanhueza and Saurabh Sharma

{"title":"Unveiling Physical Conditions and Star Formation Processes in the G47 Filamentary Cloud","authors":"O. R. Jadhav, L. K. Dewangan, A. Haj Ismail, N. K. Bhadari, A. K. Maity, Ram Kesh Yadav, Moustafa Salouci, Patricio Sanhueza and Saurabh Sharma","doi":"10.3847/1538-4357/adcee4","DOIUrl":"https://doi.org/10.3847/1538-4357/adcee4","url":null,"abstract":"We present a multiwavelength study of the filamentary cloud G47 (d ∼ 4.44 kpc), which hosts the mid-infrared bubbles N98, B1, and B2. The SMGPS 1.3 GHz continuum map detects ionized emission toward all the bubbles, marking the first detection of ionized emission toward the B2 bubble. Analysis of the unWISE 12.0 μm image, the Spitzer 8.0 μm image, and the Herschel column density and temperature maps reveals two previously unreported hub–filament system candidates associated with the H ii regions B2 and N98, which are powered by massive OB stars. This indirectly favors the applicability of a global nonisotropic collapse scenario for massive star formation in N98 and B2. The position–position–velocity diagram of FUGIN 13CO (1–0) shows significant velocity variations from 61 to 53 km s−1 toward areas between B2 and N98, where the magnetic field morphology exhibits significant curvature and high velocity dispersion (i.e., 2.3–3.1 km s−1) is observed. This may be explained by the expansion of the H ii regions B2 and N98. The energy budget of the cloud, estimated using SOFIA/HAWC+ and molecular line data, suggests that the magnetic field dominates over turbulence and gravity in G47. Furthermore, the radial column density and velocity profiles of G47 display signatures of converging flows in a sheet-like structure. The relative orientations between the magnetic field and local gravity suggest that G47 may undergo gravitational contraction along the magnetic field lines once it becomes magnetically supercritical.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"52 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144218752","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Constraining the Mass of a Hypothetical Secondary Black Hole in M87 with the NANOGrav 15 yr Data Set 用nanogravity 15年数据集约束M87假想次级黑洞的质量

The Astrophysical Journal Pub Date : 2025-06-04 DOI: 10.3847/1538-4357/adceb6

Motoki Kino, Masahiro Nagashima, Hyunwook Ro, Yuzhu Cui, Kazuhiro Hada and Jongho Park

{"title":"Constraining the Mass of a Hypothetical Secondary Black Hole in M87 with the NANOGrav 15 yr Data Set","authors":"Motoki Kino, Masahiro Nagashima, Hyunwook Ro, Yuzhu Cui, Kazuhiro Hada and Jongho Park","doi":"10.3847/1538-4357/adceb6","DOIUrl":"https://doi.org/10.3847/1538-4357/adceb6","url":null,"abstract":"Galaxy mergers, each hosting a supermassive black hole (SMBH), are thought to form SMBH binaries. Motivated by recent observations from the East Asian Very Long Baseline Interferometry (VLBI) Network (EAVN) showing periodic behavior in the M87 jet, a precession of about 11 yr and a transverse oscillation of about 0.9 yr, we constrain the mass of a hypothetical secondary black hole orbiting the primary SMBH in M87. To constrain the mass ratio between the primary SMBH (M1) and the secondary black hole (M2) defined as q ≡ M2/M1 ≤ 1, and the length of the semimajor axis of the binary system (a), we impose the following three constraints: (i) the lower limit of a, below which the SMBH binary is expected to merge; (ii) the strain amplitude of the gravitational-wave background at nanohertz frequencies shown in the NANOGrav 15 yr data set; and (iii) a finite length of the semimajor axis of M1, which can induce periodic behavior in the jet. By combining these constraints, we obtain the allowed parameter space for q and a. If either of the EAVN-detected periods (T) corresponds to the binary’s orbital period, the allowed range of q is 6.9 × 10−3 ≤ q ≤ 4.2 × 10−2 for T ≈ 11 yr, and 3.7 × 10−2 ≤ q ≤ 1 for T ≈ 0.9 yr. VLBI astrometric monitoring of the jet base of M87 is essential to explore the allowed parameter space for q and a.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"10 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144228698","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Increased Lyα Opacity in White Dwarf Photospheres from Transient H− Resonances 瞬态H−共振导致白矮星光球Lyα不透明度增加

The Astrophysical Journal Pub Date : 2025-06-04 DOI: 10.3847/1538-4357/adc9ae

Thomas A. Gomez, Mark C. Zammit, Jackson R. White, Evgeny Stambulchik, Ivan Hubeny, Igor Bray, Christopher J. Fontes, Michael H. Montgomery, Bart H. Dunlap and Donald E. Winget

{"title":"Increased Lyα Opacity in White Dwarf Photospheres from Transient H− Resonances","authors":"Thomas A. Gomez, Mark C. Zammit, Jackson R. White, Evgeny Stambulchik, Ivan Hubeny, Igor Bray, Christopher J. Fontes, Michael H. Montgomery, Bart H. Dunlap and Donald E. Winget","doi":"10.3847/1538-4357/adc9ae","DOIUrl":"https://doi.org/10.3847/1538-4357/adc9ae","url":null,"abstract":"The structure and emergent flux of hydrogen atmosphere white dwarfs depend on the opacity of the Lyα and Lyβ spectral lines. The opacity here is set by the strength and broadening of these lines; the latter is dictated by the far line wing, which is in the “quasi-static” limit of electron broadening, placing it in the incomplete collision regime, and describes the transient parts of electron and ion collisions. These transient stages of the collision form resonances: In the case of ions, they manifest as molecular resonances, while for electrons they are H− resonances, both of which can only be captured quantum-mechanically. Quantum-mechanical calculations have historically preserved only a handful of broadening terms that are most important near the center of the line. However, in the wings of the line, the previously neglected terms that describe the transient stages of the collision need to be included. This requirement arises because, in the line wings, the broadening from the 1s ground state, which is generally assumed to be extremely small compared to the broadening of the upper state, is no longer negligible within a quantum-mechanical model that takes into account exchange interactions. The inclusion of all the transient terms results in asymmetries and extra broadening. The increased broadening of Lyα increases the opacity at the energy where most of the flux leaves the star. The broader Lyα lines also impact the visible flux, raising it by an amount that exceeds previously estimated errors.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"9 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144229115","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

The Origin of the Cluster of Local Interstellar Clouds 本地星际云团的起源

The Astrophysical Journal Pub Date : 2025-06-04 DOI: 10.3847/1538-4357/adc920

Catherine Zucker, Seth Redfield, Sara Starecheski, Ralf Konietzka and Jeffrey L. Linsky

{"title":"The Origin of the Cluster of Local Interstellar Clouds","authors":"Catherine Zucker, Seth Redfield, Sara Starecheski, Ralf Konietzka and Jeffrey L. Linsky","doi":"10.3847/1538-4357/adc920","DOIUrl":"https://doi.org/10.3847/1538-4357/adc920","url":null,"abstract":"The interstellar medium within ≈15 pc of the Sun consists of a complex of 15 diffuse, partially ionized clouds. Located within the Local Bubble, these clouds, known as the Cluster of Local Interstellar Clouds (CLIC), constitute the interstellar environment impinging upon our heliosphere. While each individual cloud can be modeled with a distinct velocity vector, the complex demonstrates a coherent bulk motion suggestive of a common origin. Here, we examine two theories for the origin of the CLIC: that it formed due to an ionization front associated with nearby Strömgren spheres and/or due to a nearby supernova explosion that occurred within the pre-evacuated cavity of the Local Bubble. Tracing back the trajectory of the clouds, we disfavor a purely Strömgren sphere origin, given the CLIC’s position interior to the surface of the most significant nearby Strömgren sphere and its motion transverse to the sphere’s trajectory. Turning to a supernova origin, we model the formation of the CLIC assuming individual clouds have been swept up over time due to the expansion of a supernova remnant in its pressure-driven snowplow phase. We find that the 3D spatial-dynamical properties of the CLIC can be explained by the most recent supernova that exploded in the nearby Upper Centaurus Lupus cluster ≈1.2 Myr ago and propagated into an ambient density of n ≈ 0.04 cm−3. Our model predicts that the formation of the individual CLIC clouds occurred progressively over the past 1 Myr and offers a natural explanation for the observed distribution, column density, temperature, and magnetic field structure of the complex.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"11 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144218750","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

The Tip of Red Giant Branch Distances to Nearby Dwarf Galaxies WLM and Sextans A with JWST 用JWST观测红巨星分支到附近矮星系WLM和六分星A的距离

The Astrophysical Journal Pub Date : 2025-06-04 DOI: 10.3847/1538-4357/add52e

Ziming Yan, Shu Wang, Xiaodian Chen and Licai Deng

{"title":"The Tip of Red Giant Branch Distances to Nearby Dwarf Galaxies WLM and Sextans A with JWST","authors":"Ziming Yan, Shu Wang, Xiaodian Chen and Licai Deng","doi":"10.3847/1538-4357/add52e","DOIUrl":"https://doi.org/10.3847/1538-4357/add52e","url":null,"abstract":"Distance measurements to extragalactic systems that are both accurate and precise are cornerstones of modern astrophysics, underpinning the calibration of standard candles and the determination of the Hubble constant. Dwarf galaxies, such as Wolf–Lundmark–Melotte (WLM) and Sextans A, provide valuable laboratories for testing distance scales across different stellar populations. In this work, we utilize the high sensitivity and spatial resolution of the James Webb Space Telescope to measure the distances to WLM and Sextans A using the tip of the red giant branch (TRGB) method. Adopting the TRGB absolute magnitude calibrated by NGC 4258, we determine distance moduli of μ0,WLM = 24.977 ± 0.018(stat) ± 0.056(sys) mag for WLM and μ0,SexA = 25.740 ± 0.011(stat) ± 0.057(sys) mag for Sextans A. Our results are consistent within a 3% distance uncertainty with previous measurements based on TRGB, Cepheids, and J-Region Asymptotic Giant Branch methods. With improved distance measurements in the future, these two galaxies have the potential to serve as additional anchor points for TRGB calibration and reduce the TRGB-based distance uncertainty to below 2%.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"331 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144218756","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Systematic Search for Blue Hypervelocity Stars from LAMOST Survey LAMOST巡天中蓝色超高速恒星的系统搜索

The Astrophysical Journal Pub Date : 2025-06-04 DOI: 10.3847/1538-4357/adcebe

Yongkang Sun, Yang Huang, Jifeng Liu, Haozhu Fu, Huawei Zhang, Yinbi Li, Cuihua Du, Jianrong Shi and Xiao Kong

{"title":"Systematic Search for Blue Hypervelocity Stars from LAMOST Survey","authors":"Yongkang Sun, Yang Huang, Jifeng Liu, Haozhu Fu, Huawei Zhang, Yinbi Li, Cuihua Du, Jianrong Shi and Xiao Kong","doi":"10.3847/1538-4357/adcebe","DOIUrl":"https://doi.org/10.3847/1538-4357/adcebe","url":null,"abstract":"Hypervelocity stars (HVSs) represent a unique class of objects capable of escaping the gravitational pull of the Milky Way due to extreme acceleration events, such as close encounters with the supermassive black hole at the Galactic center (GC), supernova explosions in binary systems, or multibody dynamical interactions. Finding and studying HVSs are crucial to exploring these ejection mechanisms, characterizing central black holes, probing the GC environment, and revealing the distribution of dark matter in our Galaxy. The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) spectroscopic surveys have so far identified four B-type unbound HVSs. To expand this sample with the second-phase LAMOST survey that started in 2018, we conducted a systematic search for early-type HVSs using the LAMOST Data Release 10. We identified 125 early-type high-velocity candidates with total velocities exceeding 300 km s−1. Among them, we report 10 new unbound B- and A-type HVS candidates (designated LAMOST-HVS 5 through LAMOST-HVS 14), tripling the number of unbound HVSs previously identified by LAMOST. Kinematic analyses suggest that these newly discovered HVS candidates likely originated either from the GC or via dynamical interactions. Future high-resolution follow-up observations promise to refine the stellar parameters, distances, and elemental abundances of these candidates, thereby providing deeper insights into their origins and broadening their potential applications across astrophysics.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"39 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144228699","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A 7 day Multiwavelength Flare Campaign on AU Mic. II. Electron Densities and Kinetic Energies from High-frequency Radio Flares 7天多波长耀斑运动在AU麦克风上。2。高频射电耀斑的电子密度和动能

The Astrophysical Journal Pub Date : 2025-06-04 DOI: 10.3847/1538-4357/adc565

Isaiah I. Tristan, Rachel A. Osten, Yuta Notsu, Adam F. Kowalski, Alexander Brown, Graeme L. White, Carol A. Grady, Todd J. Henry and Eliot Halley Vrijmoet

{"title":"A 7 day Multiwavelength Flare Campaign on AU Mic. II. Electron Densities and Kinetic Energies from High-frequency Radio Flares","authors":"Isaiah I. Tristan, Rachel A. Osten, Yuta Notsu, Adam F. Kowalski, Alexander Brown, Graeme L. White, Carol A. Grady, Todd J. Henry and Eliot Halley Vrijmoet","doi":"10.3847/1538-4357/adc565","DOIUrl":"https://doi.org/10.3847/1538-4357/adc565","url":null,"abstract":"M dwarfs are the most common type of star in the solar neighborhood, and many exhibit frequent and highly energetic flares. To better understand these events across the electromagnetic spectrum, a campaign observed AU Mic (dM1e) over 7 days from the X-ray to radio regimes. Here, we present high-time-resolution light curves from the Karl G. Jansky Very Large Array (VLA) Ku band (12–18 GHz) and the Australia Telescope Compact Array (ATCA) K band (16–25 GHz), which observe gyrosynchrotron radiation and directly probe the action of accelerated electrons within flaring loops. Observations reveal 16 VLA and three ATCA flares of varying shapes and sizes, from a short (30 s) spiky burst to a long-duration (∼5 hr) decaying exponential. The Ku-band spectral index is found to often evolve during flares. Both rising and falling spectra are observed in the Ku band, indicating optically thick and thin flares, respectively. Estimations from optically thick radiation indicate higher loop-top magnetic field strengths (∼1 kG) and sustained electron densities (∼106 cm−3) than previous observations of large M dwarf flares. We estimate the total kinetic energies of gyrating electrons in optically thin flares to be between 1032 and 1034 erg when the local magnetic field strength is between 500 and 700 G. These energies are able to explain the combined radiated energies from multiwavelength observations. Overall, values are more aligned with modern radiative-hydrodynamic simulations of M dwarf flares, and future modeling efforts will better constrain findings.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"17 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144229114","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0